EXPOSURES › CVE-2025-27915
CVE-2025-27915
HIGH ⌖ ON CISA KEV · EXPLOITEDSynacor Zimbra CSVuln
Zimbra Collaboration Suite suffered an unpatched XSS vulnerability allowing remote code execution.
Shame score — Chronic vulnerability management failure leading to active exploitation by ransomware.
▸ RECOMMENDED ACTION Actively exploited (CISA KEV) — remediate now, ahead of your normal patch cycle.
Synacor Zimbra Collaboration Suite (ZCS) contains a cross-site scripting vulnerability that exists in the Classic Web Client due to insufficient sanitization of HTML content in ICS files. When a user views an e-mail message containing a malicious ICS entry, its embedded JavaScript executes via an ontoggle event inside a tag. This allows an attacker to run arbitrary JavaScript within the victim's session, potentially leading to unauthorized actions such as setting e-mail filters to redirect messages to an attacker-controlled address. As a result, an attacker can perform unauthorized actions on the victim's account, including e-mail redirection and data exfiltration.